Heretofore, an image forming apparatus such as a laser printer, to which a developing cartridge containing a developer (hereafter referred to as a toner) can be detachably attached, has been known. Normally, the developing cartridge is equipped, in a developer container for containing the toner, with an agitation member (hereafter referred to as an agitator) for agitating the toner and supplying the toner to a developer carrier (hereafter referred to as a developing roller).
The agitator includes a rotary shaft and a plate-like agitation portion projecting from the rotary shaft in a direction perpendicular to the rotary shaft.
Both ends of the rotary shaft are rotatably supported on a developing cartridge casing sidewall forming the developer container. Particularly, one end of the rotary shaft is provided in such a way as to pass through the casing sidewall, and a drive member (hereafter referred to as a gear) for transmitting a driving force to the rotary shaft is fixed to the pass-through portion.
Also, the gear is provided with a detected portion for causing a detector portion disposed in an image forming apparatus to detect a rotary condition of the rotary shaft (for example, refer to JP-A-2004-191559).
In the thus configured developing cartridge, by the rotary shaft and thus the agitation portion of the agitator rotating in response to a driving force from the image forming apparatus via the gear, the toner in the developer container is agitated and supplied to the developing roller. Furthermore, the rotary condition of the rotary shaft is detected by the detector portion via the detected portion.